Biomedical subjects

P S Cornaglia

Publications and source records attributed to P S Cornaglia.

4 recordsLinked to original sources

PubMed2006

Time evolution of the electronic structure of 1T-TaS2 through the insulator-metal transition.

Femtosecond time-resolved photoemission is used to investigate the time evolution of electronic structure in the Mott insulator 1T-TaS2. A collapse of the electronic gap is observed within 100 femtoseconds after optical excitation. The photoemission spectra and the spectral function calculated by dynamical mean field theory show that this insulator-metal transition is driven solely by hot electrons. A coherently excited lattice displacement results in a periodic shift of the spectra lasting for 20 ps without perturbing the insulating phase. This capability to disentangle electronic and phononic excitations opens new directions to study electron correlation in solids.

Journal Article↗

PubMed2006

Universal distribution of Kondo temperatures in dirty metals.

Kondo screening of diluted magnetic impurities in a disordered host is studied analytically and numerically in one, two, and three dimensions. It is shown that in the T(K) --> 0 limit the distribution of Kondo temperatures has a universal form P(T(K)) approximately T(K) (-a) that holds in the insulating phase and persists in the metallic phase close to the metal-insulator transition. Moreover, the exponent depends only on the dimensionality. The most important consequence of this result is that the T dependence of thermodynamic properties is smooth across the metal-insulator transition in three dimensional systems.

Journal Article↗

PubMed2004

Many-body effects on the transport properties of single-molecule devices.

The conductance through a molecular device including electron-electron and electron-phonon interactions is calculated using the numerical renormalization group method. At low temperatures and weak electron-phonon coupling the properties of the conductance can be explained in terms of the standard Kondo model with renormalized parameters. At large electron-phonon coupling a charge analog of the Kondo effect takes place that can be mapped into an anisotropic Kondo model. In this regime the molecule is strongly polarized by a gate voltage which leads to rectification in the current-voltage characteristics of the molecular junction.

Journal Article↗

PubMed2003

Transport through quantum dots in mesoscopic circuits.

We study the transport through a quantum dot, in the Kondo Coulomb blockade valley, embedded in a mesoscopic device with finite wires. The quantization of states in the circuit that hosts the quantum dot gives rise to finite size effects. These effects make the conductance sensitive to the ratio of the Kondo screening length to the wires length and provide a way of measuring the Kondo cloud. We present results obtained with the numerical renormalization group for a wide range of physically accessible parameters.

Journal Article↗